Certain embodiments of the present invention generally relate to an air flow detecting system for a dryer system, a dryer system using an air flow detecting system, and a method of operating a dryer system based on air flow.
Conventional clothes dryers heat a compartment holding wet clothes that dry by evaporation. The effectiveness of heat in drying clothes depends on the relative humidity and temperature of the air in the compartment. As water evaporates from the clothes into the air, the air in the compartment becomes more saturated with water vapor and, consequently, less effective for drying. As a result, it is important to provide ventilation in the drying compartment to exhaust humid air and minimize the amount of water vapor in the air in the drying compartment.
Clothes dryers frequently provide an exhaust passage or duct to provide a path for air to leave a dryer. Typically, a dryer will also include a lint trap somewhere along the exhaust passage. The filling or clogging of the lint trap causes blockage in the exhaust passage and inhibits the flow of air out of the drying compartment. Often the exhaust passage includes a length of flexible hose. If the hose becomes pinched or if the hose kinks, the air flow from the dryer will be inhibited. Thus, a clogged lint trap, a kinked hose, or other situations may block the air flow out of the dryer.
The reduction of air flow through the exhaust passage may result in serious consequences. If the hot, humid air from the dryer is not exhausted, the continued addition of heat to the air from the heater may raise the temperature to dangerous levels. As the humid air is trapped in the dryer, the drying compartment air will become saturated with water vapor and no longer removes moisture from the clothes. As a result, the clothes will not dry during the drying cycle. Further, the increased temperature may damage clothes and/or dryer components. More seriously, the elevated temperature may result in the clothes catching fire which may not only destroy the clothes, but also may spread to the house or building.
One conventional approach to this problem has been to provide a temperature sensor. When the temperature in the compartment reaches a predetermined level, the temperature sensor acts to turn the dryer and/or the heater off before the temperature rises high enough to cause a fire. Temperature monitors, however, do not provide an indication of actual air flow, which is a key factor in adequate drying. For example, if air flow is blocked but the temperature does not rise high enough to turn the dryer off before the drying cycle ends, the clothes will not be dry if the trapped air was too humid to allow adequate evaporation. Conventional temperature monitoring systems do not indicate to the user that low air flow may exist, and that clothes are not being dried effectively. Further, conventional temperature monitoring systems do not provide a warning of when the dryer is operating in an ineffective but not yet dangerous situation such as before the temperature reaches a critical level but air flow is impeded. These and other drawbacks to conventional systems may result in ineffective drying, damage to clothes, damage to dryer components, and the potential for fire.
Pressure sensors have also been used in the past with dryer systems. However, these do not provide a direct measure of air flow, and can depend on external pressure. Additionally, they do not send a signal usable by a processor.
It is an object of at least certain embodiments of the present invention to overcome the above-noted and other disadvantages of conventional dryer systems.
At least one embodiment of the present invention is provided including a dryer system having a drying compartment for holding clothing or other articles to be dried, a heater for providing heat to assist in drying the articles in the drying compartment, an exhaust passage through which air from the drying compartment is discharged, a detector for monitoring air flow through the exhaust passage, and a processor for controlling the operation of the dryer system based on an output of the detecting system. Optionally, the detecting system may include a sensor and a mechanical element. The sensor is responsive to the position of the mechanical element caused by air flow in the exhaust passage.
In accordance with at least one alternative embodiment, the dryer system includes a shaft, a fan, and a sensor. The fan is mounted on the shaft, and the fan and shaft rotate in response to air flow through the exhaust passage. The sensor, for example, a DC generator, senses rotation of the shaft.
In accordance with at least one alternative embodiment, the shaft comprises a hole, and the sensor comprises a light emitting source and a light receiver. The shaft, hole, light emitting source, and light receiver are configured so that light from the light emitting source is directed through the hole at the light receiving source, and rotation of the shaft causes the light to be received intermittently by the light receiver.
In accordance with at least one alternative embodiment, the dryer system includes a detecting system that comprises an air flow sensor that provides an intermittent signal to a processor. Each interruption of the signal varies based on the rate of air flow through the exhaust passage.
Optionally, the detecting system may generate a signal directly proportional to the rate of air flow through the exhaust passage. Optionally, the detecting system may directly monitor the air flow through the exhaust passage. Further optionally, the detector may monitor the air flow independent of atmospheric pressure.
In accordance with at least one alternative embodiment, the processor of the dryer system operates to modulate one or a plurality of operating parameters in response to the air flow rate. For example, the processor may operate to turn at least part of the dryer system off when the air flow through the exhaust opening is less than a predetermined rate. Optionally, the processor may provide a perceptible warning indication, such as a light, when the air flow through the exhaust opening is less than a first predetermined rate, and to turn at least part of the dryer system off when the air flow through the exhaust opening is less than a second predetermined rate.
At least one embodiment of the present invention is provided including an air flow detecting system for monitoring air flow in a dryer system. The dryer system has an exhaust passage through which air from a drying compartment flows. The air flow detecting system includes a detector for monitoring a rate at which air from the drying compartment travels through the exhaust passage, and a signal generator. The signal generator is responsive to the detector and generates an electrical signal for which at least one of phase, frequency, voltage, or current varies over a continuous range based on a measured flow rate.
Optionally, the electrical signal generated may be directly proportional to the rate of air flow. Optionally, the signal generator may provide an intermittent signal, where each interruption of the signal varies based on the rate of air flow.
At least one embodiment of the present invention provides a method of operating a dryer system having a heater and an exhaust passage through which air from a drying compartment flows. The method comprises the steps of detecting a flow rate, generating an electrical signal based on the detected flow rate, and controlling the operation of the dryer system responsive to the electrical signal. At least one of the phase, frequency, voltage, or current of the electrical signal varies based on the detected flow rate.
In accordance with at least one alternative embodiment, the method includes the steps of converting the air flow rate to a mechanical position and converting the mechanical position to an electrical signal. Alternatively, and in accordance with at least one alternative embodiment, the method includes the steps of converting the air flow rate to a mechanical motion and converting the mechanical motion to an electrical signal. Optionally, the method may comprise the steps of providing a light source, interrupting the light source at a phase or frequency corresponding to the air flow rate, and converting the interruption of the light to an electrical signal.
In accordance with at least one alternative embodiment, the method of operating a dryer system also includes comparing the detected flow rate to a predetermined rate, and interrupting the operation of at least a part of the dryer system if the detected flow rate is less than the predetermined rate. Optionally, the method may comprise comparing the detected flow rate to first and second predetermined rates, providing a warning signal if the detected flow rate is less than the first predetermined rate, and interrupting the operation of at least a part of said dryer system if the detected flow rate is less than the second predetermined rate.